libstdc++
stdio_sync_filebuf.h
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1 // Iostreams wrapper for stdio FILE* -*- C++ -*-
2 
3 // Copyright (C) 2003, 2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file ext/stdio_sync_filebuf.h
26  * This file is a GNU extension to the Standard C++ Library.
27  */
28 
29 #ifndef _STDIO_SYNC_FILEBUF_H
30 #define _STDIO_SYNC_FILEBUF_H 1
31 
32 #pragma GCC system_header
33 
34 #include <streambuf>
35 #include <unistd.h>
36 #include <cstdio>
37 #include <bits/c++io.h> // For __c_file
38 
39 #ifdef _GLIBCXX_USE_WCHAR_T
40 #include <cwchar>
41 #endif
42 
43 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
44 
45  /// class stdio_sync_filebuf.
46  template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
47  class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
48  {
49  public:
50  // Types:
51  typedef _CharT char_type;
52  typedef _Traits traits_type;
53  typedef typename traits_type::int_type int_type;
54  typedef typename traits_type::pos_type pos_type;
55  typedef typename traits_type::off_type off_type;
56 
57  private:
58  // Underlying stdio FILE
59  std::__c_file* const _M_file;
60 
61  // Last character gotten. This is used when pbackfail is
62  // called from basic_streambuf::sungetc()
63  int_type _M_unget_buf;
64 
65  public:
66  explicit
67  stdio_sync_filebuf(std::__c_file* __f)
68  : _M_file(__f), _M_unget_buf(traits_type::eof())
69  { }
70 
71  /**
72  * @return The underlying FILE*.
73  *
74  * This function can be used to access the underlying "C" file pointer.
75  * Note that there is no way for the library to track what you do
76  * with the file, so be careful.
77  */
78  std::__c_file* const
79  file() { return this->_M_file; }
80 
81  protected:
82  int_type
83  syncgetc();
84 
85  int_type
86  syncungetc(int_type __c);
87 
88  int_type
89  syncputc(int_type __c);
90 
91  virtual int_type
92  underflow()
93  {
94  int_type __c = this->syncgetc();
95  return this->syncungetc(__c);
96  }
97 
98  virtual int_type
99  uflow()
100  {
101  // Store the gotten character in case we need to unget it.
102  _M_unget_buf = this->syncgetc();
103  return _M_unget_buf;
104  }
105 
106  virtual int_type
107  pbackfail(int_type __c = traits_type::eof())
108  {
109  int_type __ret;
110  const int_type __eof = traits_type::eof();
111 
112  // Check if the unget or putback was requested
113  if (traits_type::eq_int_type(__c, __eof)) // unget
114  {
115  if (!traits_type::eq_int_type(_M_unget_buf, __eof))
116  __ret = this->syncungetc(_M_unget_buf);
117  else // buffer invalid, fail.
118  __ret = __eof;
119  }
120  else // putback
121  __ret = this->syncungetc(__c);
122 
123  // The buffered character is no longer valid, discard it.
124  _M_unget_buf = __eof;
125  return __ret;
126  }
127 
128  virtual std::streamsize
129  xsgetn(char_type* __s, std::streamsize __n);
130 
131  virtual int_type
132  overflow(int_type __c = traits_type::eof())
133  {
134  int_type __ret;
135  if (traits_type::eq_int_type(__c, traits_type::eof()))
136  {
137  if (std::fflush(_M_file))
138  __ret = traits_type::eof();
139  else
140  __ret = traits_type::not_eof(__c);
141  }
142  else
143  __ret = this->syncputc(__c);
144  return __ret;
145  }
146 
147  virtual std::streamsize
148  xsputn(const char_type* __s, std::streamsize __n);
149 
150  virtual int
151  sync()
152  { return std::fflush(_M_file); }
153 
154  virtual std::streampos
155  seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
156  std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
157  {
158  std::streampos __ret(std::streamoff(-1));
159  int __whence;
160  if (__dir == std::ios_base::beg)
161  __whence = SEEK_SET;
162  else if (__dir == std::ios_base::cur)
163  __whence = SEEK_CUR;
164  else
165  __whence = SEEK_END;
166 #ifdef _GLIBCXX_USE_LFS
167  if (!fseeko64(_M_file, __off, __whence))
168  __ret = std::streampos(ftello64(_M_file));
169 #else
170  if (!fseek(_M_file, __off, __whence))
171  __ret = std::streampos(std::ftell(_M_file));
172 #endif
173  return __ret;
174  }
175 
176  virtual std::streampos
177  seekpos(std::streampos __pos,
178  std::ios_base::openmode __mode =
180  { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
181  };
182 
183  template<>
184  inline stdio_sync_filebuf<char>::int_type
185  stdio_sync_filebuf<char>::syncgetc()
186  { return std::getc(_M_file); }
187 
188  template<>
189  inline stdio_sync_filebuf<char>::int_type
190  stdio_sync_filebuf<char>::syncungetc(int_type __c)
191  { return std::ungetc(__c, _M_file); }
192 
193  template<>
194  inline stdio_sync_filebuf<char>::int_type
195  stdio_sync_filebuf<char>::syncputc(int_type __c)
196  { return std::putc(__c, _M_file); }
197 
198  template<>
199  inline std::streamsize
200  stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
201  {
202  std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
203  if (__ret > 0)
204  _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
205  else
206  _M_unget_buf = traits_type::eof();
207  return __ret;
208  }
209 
210  template<>
211  inline std::streamsize
212  stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
213  { return std::fwrite(__s, 1, __n, _M_file); }
214 
215 #ifdef _GLIBCXX_USE_WCHAR_T
216  template<>
217  inline stdio_sync_filebuf<wchar_t>::int_type
218  stdio_sync_filebuf<wchar_t>::syncgetc()
219  { return std::getwc(_M_file); }
220 
221  template<>
222  inline stdio_sync_filebuf<wchar_t>::int_type
223  stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
224  { return std::ungetwc(__c, _M_file); }
225 
226  template<>
227  inline stdio_sync_filebuf<wchar_t>::int_type
228  stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
229  { return std::putwc(__c, _M_file); }
230 
231  template<>
232  inline std::streamsize
233  stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
234  {
235  std::streamsize __ret = 0;
236  const int_type __eof = traits_type::eof();
237  while (__n--)
238  {
239  int_type __c = this->syncgetc();
240  if (traits_type::eq_int_type(__c, __eof))
241  break;
242  __s[__ret] = traits_type::to_char_type(__c);
243  ++__ret;
244  }
245 
246  if (__ret > 0)
247  _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
248  else
249  _M_unget_buf = traits_type::eof();
250  return __ret;
251  }
252 
253  template<>
254  inline std::streamsize
255  stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
256  std::streamsize __n)
257  {
258  std::streamsize __ret = 0;
259  const int_type __eof = traits_type::eof();
260  while (__n--)
261  {
262  if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
263  break;
264  ++__ret;
265  }
266  return __ret;
267  }
268 #endif
269 
270 #if _GLIBCXX_EXTERN_TEMPLATE
271  extern template class stdio_sync_filebuf<char>;
272 #ifdef _GLIBCXX_USE_WCHAR_T
273  extern template class stdio_sync_filebuf<wchar_t>;
274 #endif
275 #endif
276 
277 _GLIBCXX_END_NAMESPACE
278 
279 #endif
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:383
ISO C++ entities toplevel namespace is std.
long long streamoff
Type used by fpos, char_traits, and char_traits.
Definition: postypes.h:94
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:404
std::__c_file *const file()
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:98
GNU extensions for public use.
class stdio_sync_filebuf.
fpos< mbstate_t > streampos
File position for char streams.
Definition: postypes.h:228
Class representing stream positions.
Definition: postypes.h:112
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:407
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:386